noun
- the escape of combustion gases past the piston rings in an internal combustion engine into the crankcase
Usage: automotive/mechanical term; also written as blow-by or blow by
Examples
- Excessive blowby can indicate worn piston rings that need replacement.
- The mechanic detected blowby during the engine diagnostic test.
- Blowby gases are typically routed back into the intake manifold through a PCV system.
- High blowby rates reduce engine efficiency and increase oil contamination.
- Modern engines are designed to minimize blowby through precision manufacturing.